// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// On Linux, when the user tries to launch a second copy of chrome, we check
// for a socket in the user's profile directory. If the socket file is open we
// send a message to the first chrome browser process with the current
// directory and second process command line flags. The second process then
// exits.
//
// Because many networked filesystem implementations do not support unix domain
// sockets, we create the socket in a temporary directory and create a symlink
// in the profile. This temporary directory is no longer bound to the profile,
// and may disappear across a reboot or login to a separate session. To bind
// them, we store a unique cookie in the profile directory, which must also be
// present in the remote directory to connect. The cookie is checked both before
// and after the connection. /tmp is sticky, and different Chrome sessions use
// different cookies. Thus, a matching cookie before and after means the
// connection was to a directory with a valid cookie.
//
// We also have a lock file, which is a symlink to a non-existent destination.
// The destination is a string containing the hostname and process id of
// chrome's browser process, eg. "SingletonLock -> example.com-9156". When the
// first copy of chrome exits it will delete the lock file on shutdown, so that
// a different instance on a different host may then use the profile directory.
//
// If writing to the socket fails, the hostname in the lock is checked to see if
// another instance is running a different host using a shared filesystem (nfs,
// etc.) If the hostname differs an error is displayed and the second process
// exits. Otherwise the first process (if any) is killed and the second process
// starts as normal.
//
// When the second process sends the current directory and command line flags to
// the first process, it waits for an ACK message back from the first process
// for a certain time. If there is no ACK message back in time, then the first
// process will be considered as hung for some reason. The second process then
// retrieves the process id from the symbol link and kills it by sending
// SIGKILL. Then the second process starts as normal.
//
// TODO(james.su@gmail.com): Add unittest for this class.
#include "chrome/browser/process_singleton.h"
#include <errno.h>
#include <fcntl.h>
#include <gdk/gdk.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
#include <cstring>
#include <set>
#include <string>
#include "base/base_paths.h"
#include "base/basictypes.h"
#include "base/command_line.h"
#include "base/eintr_wrapper.h"
#include "base/file_path.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "base/message_loop.h"
#include "base/path_service.h"
#include "base/process_util.h"
#include "base/rand_util.h"
#include "base/safe_strerror_posix.h"
#include "base/stl_util-inl.h"
#include "base/string_number_conversions.h"
#include "base/string_split.h"
#include "base/sys_string_conversions.h"
#include "base/threading/platform_thread.h"
#include "base/time.h"
#include "base/timer.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/browser_process.h"
#if defined(TOOLKIT_GTK)
#include "chrome/browser/ui/gtk/process_singleton_dialog.h"
#endif
#include "chrome/browser/io_thread.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/profiles/profile_manager.h"
#include "chrome/browser/ui/browser_init.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/chrome_switches.h"
#include "content/browser/browser_thread.h"
#include "grit/chromium_strings.h"
#include "grit/generated_resources.h"
#include "net/base/net_util.h"
#include "ui/base/l10n/l10n_util.h"
const int ProcessSingleton::kTimeoutInSeconds;
namespace {
const char kStartToken[] = "START";
const char kACKToken[] = "ACK";
const char kShutdownToken[] = "SHUTDOWN";
const char kTokenDelimiter = '\0';
const int kMaxMessageLength = 32 * 1024;
const int kMaxACKMessageLength = arraysize(kShutdownToken) - 1;
const char kLockDelimiter = '-';
// Set a file descriptor to be non-blocking.
// Return 0 on success, -1 on failure.
int SetNonBlocking(int fd) {
int flags = fcntl(fd, F_GETFL, 0);
if (-1 == flags)
return flags;
if (flags & O_NONBLOCK)
return 0;
return fcntl(fd, F_SETFL, flags | O_NONBLOCK);
}
// Set the close-on-exec bit on a file descriptor.
// Returns 0 on success, -1 on failure.
int SetCloseOnExec(int fd) {
int flags = fcntl(fd, F_GETFD, 0);
if (-1 == flags)
return flags;
if (flags & FD_CLOEXEC)
return 0;
return fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
// Close a socket and check return value.
void CloseSocket(int fd) {
int rv = HANDLE_EINTR(close(fd));
DCHECK_EQ(0, rv) << "Error closing socket: " << safe_strerror(errno);
}
// Write a message to a socket fd.
bool WriteToSocket(int fd, const char *message, size_t length) {
DCHECK(message);
DCHECK(length);
size_t bytes_written = 0;
do {
ssize_t rv = HANDLE_EINTR(
write(fd, message + bytes_written, length - bytes_written));
if (rv < 0) {
if (errno == EAGAIN || errno == EWOULDBLOCK) {
// The socket shouldn't block, we're sending so little data. Just give
// up here, since NotifyOtherProcess() doesn't have an asynchronous api.
LOG(ERROR) << "ProcessSingleton would block on write(), so it gave up.";
return false;
}
PLOG(ERROR) << "write() failed";
return false;
}
bytes_written += rv;
} while (bytes_written < length);
return true;
}
// Wait a socket for read for a certain timeout in seconds.
// Returns -1 if error occurred, 0 if timeout reached, > 0 if the socket is
// ready for read.
int WaitSocketForRead(int fd, int timeout) {
fd_set read_fds;
struct timeval tv;
FD_ZERO(&read_fds);
FD_SET(fd, &read_fds);
tv.tv_sec = timeout;
tv.tv_usec = 0;
return HANDLE_EINTR(select(fd + 1, &read_fds, NULL, NULL, &tv));
}
// Read a message from a socket fd, with an optional timeout in seconds.
// If |timeout| <= 0 then read immediately.
// Return number of bytes actually read, or -1 on error.
ssize_t ReadFromSocket(int fd, char *buf, size_t bufsize, int timeout) {
if (timeout > 0) {
int rv = WaitSocketForRead(fd, timeout);
if (rv <= 0)
return rv;
}
size_t bytes_read = 0;
do {
ssize_t rv = HANDLE_EINTR(read(fd, buf + bytes_read, bufsize - bytes_read));
if (rv < 0) {
if (errno != EAGAIN && errno != EWOULDBLOCK) {
PLOG(ERROR) << "read() failed";
return rv;
} else {
// It would block, so we just return what has been read.
return bytes_read;
}
} else if (!rv) {
// No more data to read.
return bytes_read;
} else {
bytes_read += rv;
}
} while (bytes_read < bufsize);
return bytes_read;
}
// Set up a sockaddr appropriate for messaging.
void SetupSockAddr(const std::string& path, struct sockaddr_un* addr) {
addr->sun_family = AF_UNIX;
CHECK(path.length() < arraysize(addr->sun_path))
<< "Socket path too long: " << path;
base::strlcpy(addr->sun_path, path.c_str(), arraysize(addr->sun_path));
}
// Set up a socket appropriate for messaging.
int SetupSocketOnly() {
int sock = socket(PF_UNIX, SOCK_STREAM, 0);
PCHECK(sock >= 0) << "socket() failed";
int rv = SetNonBlocking(sock);
DCHECK_EQ(0, rv) << "Failed to make non-blocking socket.";
rv = SetCloseOnExec(sock);
DCHECK_EQ(0, rv) << "Failed to set CLOEXEC on socket.";
return sock;
}
// Set up a socket and sockaddr appropriate for messaging.
void SetupSocket(const std::string& path, int* sock, struct sockaddr_un* addr) {
*sock = SetupSocketOnly();
SetupSockAddr(path, addr);
}
// Read a symbolic link, return empty string if given path is not a symbol link.
FilePath ReadLink(const FilePath& path) {
FilePath target;
if (!file_util::ReadSymbolicLink(path, &target)) {
// The only errno that should occur is ENOENT.
if (errno != 0 && errno != ENOENT)
PLOG(ERROR) << "readlink(" << path.value() << ") failed";
}
return target;
}
// Unlink a path. Return true on success.
bool UnlinkPath(const FilePath& path) {
int rv = unlink(path.value().c_str());
if (rv < 0 && errno != ENOENT)
PLOG(ERROR) << "Failed to unlink " << path.value();
return rv == 0;
}
// Create a symlink. Returns true on success.
bool SymlinkPath(const FilePath& target, const FilePath& path) {
if (!file_util::CreateSymbolicLink(target, path)) {
// Double check the value in case symlink suceeded but we got an incorrect
// failure due to NFS packet loss & retry.
int saved_errno = errno;
if (ReadLink(path) != target) {
// If we failed to create the lock, most likely another instance won the
// startup race.
errno = saved_errno;
PLOG(ERROR) << "Failed to create " << path.value();
return false;
}
}
return true;
}
// Extract the hostname and pid from the lock symlink.
// Returns true if the lock existed.
bool ParseLockPath(const FilePath& path,
std::string* hostname,
int* pid) {
std::string real_path = ReadLink(path).value();
if (real_path.empty())
return false;
std::string::size_type pos = real_path.rfind(kLockDelimiter);
// If the path is not a symbolic link, or doesn't contain what we expect,
// bail.
if (pos == std::string::npos) {
*hostname = "";
*pid = -1;
return true;
}
*hostname = real_path.substr(0, pos);
const std::string& pid_str = real_path.substr(pos + 1);
if (!base::StringToInt(pid_str, pid))
*pid = -1;
return true;
}
void DisplayProfileInUseError(const std::string& lock_path,
const std::string& hostname,
int pid) {
string16 error = l10n_util::GetStringFUTF16(
IDS_PROFILE_IN_USE_LINUX,
base::IntToString16(pid),
ASCIIToUTF16(hostname),
WideToUTF16(base::SysNativeMBToWide(lock_path)),
l10n_util::GetStringUTF16(IDS_PRODUCT_NAME));
LOG(ERROR) << base::SysWideToNativeMB(UTF16ToWide(error)).c_str();
#if defined(TOOLKIT_GTK)
if (!CommandLine::ForCurrentProcess()->HasSwitch(
switches::kNoProcessSingletonDialog))
ProcessSingletonDialog::ShowAndRun(UTF16ToUTF8(error));
#endif
}
bool IsChromeProcess(pid_t pid) {
FilePath other_chrome_path(base::GetProcessExecutablePath(pid));
return (!other_chrome_path.empty() &&
other_chrome_path.BaseName() ==
FilePath(chrome::kBrowserProcessExecutableName));
}
// Return true if the given pid is one of our child processes.
// Assumes that the current pid is the root of all pids of the current instance.
bool IsSameChromeInstance(pid_t pid) {
pid_t cur_pid = base::GetCurrentProcId();
while (pid != cur_pid) {
pid = base::GetParentProcessId(pid);
if (pid < 0)
return false;
if (!IsChromeProcess(pid))
return false;
}
return true;
}
// Extract the process's pid from a symbol link path and if it is on
// the same host, kill the process, unlink the lock file and return true.
// If the process is part of the same chrome instance, unlink the lock file and
// return true without killing it.
// If the process is on a different host, return false.
bool KillProcessByLockPath(const FilePath& path) {
std::string hostname;
int pid;
ParseLockPath(path, &hostname, &pid);
if (!hostname.empty() && hostname != net::GetHostName()) {
DisplayProfileInUseError(path.value(), hostname, pid);
return false;
}
UnlinkPath(path);
if (IsSameChromeInstance(pid))
return true;
if (pid > 0) {
// TODO(james.su@gmail.com): Is SIGKILL ok?
int rv = kill(static_cast<base::ProcessHandle>(pid), SIGKILL);
// ESRCH = No Such Process (can happen if the other process is already in
// progress of shutting down and finishes before we try to kill it).
DCHECK(rv == 0 || errno == ESRCH) << "Error killing process: "
<< safe_strerror(errno);
return true;
}
LOG(ERROR) << "Failed to extract pid from path: " << path.value();
return true;
}
// A helper class to hold onto a socket.
class ScopedSocket {
public:
ScopedSocket() : fd_(-1) { Reset(); }
~ScopedSocket() { Close(); }
int fd() { return fd_; }
void Reset() {
Close();
fd_ = SetupSocketOnly();
}
void Close() {
if (fd_ >= 0)
CloseSocket(fd_);
fd_ = -1;
}
private:
int fd_;
};
// Returns a random string for uniquifying profile connections.
std::string GenerateCookie() {
return base::Uint64ToString(base::RandUint64());
}
bool CheckCookie(const FilePath& path, const FilePath& cookie) {
return (cookie == ReadLink(path));
}
bool ConnectSocket(ScopedSocket* socket,
const FilePath& socket_path,
const FilePath& cookie_path) {
FilePath socket_target;
if (file_util::ReadSymbolicLink(socket_path, &socket_target)) {
// It's a symlink. Read the cookie.
FilePath cookie = ReadLink(cookie_path);
if (cookie.empty())
return false;
FilePath remote_cookie = socket_target.DirName().
Append(chrome::kSingletonCookieFilename);
// Verify the cookie before connecting.
if (!CheckCookie(remote_cookie, cookie))
return false;
// Now we know the directory was (at that point) created by the profile
// owner. Try to connect.
sockaddr_un addr;
SetupSockAddr(socket_path.value(), &addr);
int ret = HANDLE_EINTR(connect(socket->fd(),
reinterpret_cast<sockaddr*>(&addr),
sizeof(addr)));
if (ret != 0)
return false;
// Check the cookie again. We only link in /tmp, which is sticky, so, if the
// directory is still correct, it must have been correct in-between when we
// connected. POSIX, sadly, lacks a connectat().
if (!CheckCookie(remote_cookie, cookie)) {
socket->Reset();
return false;
}
// Success!
return true;
} else if (errno == EINVAL) {
// It exists, but is not a symlink (or some other error we detect
// later). Just connect to it directly; this is an older version of Chrome.
sockaddr_un addr;
SetupSockAddr(socket_path.value(), &addr);
int ret = HANDLE_EINTR(connect(socket->fd(),
reinterpret_cast<sockaddr*>(&addr),
sizeof(addr)));
return (ret == 0);
} else {
// File is missing, or other error.
if (errno != ENOENT)
PLOG(ERROR) << "readlink failed";
return false;
}
}
} // namespace
///////////////////////////////////////////////////////////////////////////////
// ProcessSingleton::LinuxWatcher
// A helper class for a Linux specific implementation of the process singleton.
// This class sets up a listener on the singleton socket and handles parsing
// messages that come in on the singleton socket.
class ProcessSingleton::LinuxWatcher
: public MessageLoopForIO::Watcher,
public MessageLoop::DestructionObserver,
public base::RefCountedThreadSafe<ProcessSingleton::LinuxWatcher> {
public:
// A helper class to read message from an established socket.
class SocketReader : public MessageLoopForIO::Watcher {
public:
SocketReader(ProcessSingleton::LinuxWatcher* parent,
MessageLoop* ui_message_loop,
int fd)
: parent_(parent),
ui_message_loop_(ui_message_loop),
fd_(fd),
bytes_read_(0) {
// Wait for reads.
MessageLoopForIO::current()->WatchFileDescriptor(
fd, true, MessageLoopForIO::WATCH_READ, &fd_reader_, this);
timer_.Start(base::TimeDelta::FromSeconds(kTimeoutInSeconds),
this, &SocketReader::OnTimerExpiry);
}
virtual ~SocketReader() {
CloseSocket(fd_);
}
// MessageLoopForIO::Watcher impl.
virtual void OnFileCanReadWithoutBlocking(int fd);
virtual void OnFileCanWriteWithoutBlocking(int fd) {
// SocketReader only watches for accept (read) events.
NOTREACHED();
}
// Finish handling the incoming message by optionally sending back an ACK
// message and removing this SocketReader.
void FinishWithACK(const char *message, size_t length);
private:
// If we haven't completed in a reasonable amount of time, give up.
void OnTimerExpiry() {
parent_->RemoveSocketReader(this);
// We're deleted beyond this point.
}
MessageLoopForIO::FileDescriptorWatcher fd_reader_;
// The ProcessSingleton::LinuxWatcher that owns us.
ProcessSingleton::LinuxWatcher* const parent_;
// A reference to the UI message loop.
MessageLoop* const ui_message_loop_;
// The file descriptor we're reading.
const int fd_;
// Store the message in this buffer.
char buf_[kMaxMessageLength];
// Tracks the number of bytes we've read in case we're getting partial
// reads.
size_t bytes_read_;
base::OneShotTimer<SocketReader> timer_;
DISALLOW_COPY_AND_ASSIGN(SocketReader);
};
// We expect to only be constructed on the UI thread.
explicit LinuxWatcher(ProcessSingleton* parent)
: ui_message_loop_(MessageLoop::current()),
parent_(parent) {
}
// Start listening for connections on the socket. This method should be
// called from the IO thread.
void StartListening(int socket);
// This method determines if we should use the same process and if we should,
// opens a new browser tab. This runs on the UI thread.
// |reader| is for sending back ACK message.
void HandleMessage(const std::string& current_dir,
const std::vector<std::string>& argv,
SocketReader *reader);
// MessageLoopForIO::Watcher impl. These run on the IO thread.
virtual void OnFileCanReadWithoutBlocking(int fd);
virtual void OnFileCanWriteWithoutBlocking(int fd) {
// ProcessSingleton only watches for accept (read) events.
NOTREACHED();
}
// MessageLoop::DestructionObserver
virtual void WillDestroyCurrentMessageLoop() {
fd_watcher_.StopWatchingFileDescriptor();
}
private:
friend class base::RefCountedThreadSafe<ProcessSingleton::LinuxWatcher>;
virtual ~LinuxWatcher() {
STLDeleteElements(&readers_);
}
// Removes and deletes the SocketReader.
void RemoveSocketReader(SocketReader* reader);
MessageLoopForIO::FileDescriptorWatcher fd_watcher_;
// A reference to the UI message loop (i.e., the message loop we were
// constructed on).
MessageLoop* ui_message_loop_;
// The ProcessSingleton that owns us.
ProcessSingleton* const parent_;
std::set<SocketReader*> readers_;
DISALLOW_COPY_AND_ASSIGN(LinuxWatcher);
};
void ProcessSingleton::LinuxWatcher::OnFileCanReadWithoutBlocking(int fd) {
// Accepting incoming client.
sockaddr_un from;
socklen_t from_len = sizeof(from);
int connection_socket = HANDLE_EINTR(accept(
fd, reinterpret_cast<sockaddr*>(&from), &from_len));
if (-1 == connection_socket) {
PLOG(ERROR) << "accept() failed";
return;
}
int rv = SetNonBlocking(connection_socket);
DCHECK_EQ(0, rv) << "Failed to make non-blocking socket.";
SocketReader* reader = new SocketReader(this,
ui_message_loop_,
connection_socket);
readers_.insert(reader);
}
void ProcessSingleton::LinuxWatcher::StartListening(int socket) {
DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
// Watch for client connections on this socket.
MessageLoopForIO* ml = MessageLoopForIO::current();
ml->AddDestructionObserver(this);
ml->WatchFileDescriptor(socket, true, MessageLoopForIO::WATCH_READ,
&fd_watcher_, this);
}
void ProcessSingleton::LinuxWatcher::HandleMessage(
const std::string& current_dir, const std::vector<std::string>& argv,
SocketReader* reader) {
DCHECK(ui_message_loop_ == MessageLoop::current());
DCHECK(reader);
// If locked, it means we are not ready to process this message because
// we are probably in a first run critical phase.
if (parent_->locked()) {
DLOG(WARNING) << "Browser is locked";
// Send back "ACK" message to prevent the client process from starting up.
reader->FinishWithACK(kACKToken, arraysize(kACKToken) - 1);
return;
}
// Ignore the request if the browser process is already in shutdown path.
if (!g_browser_process || g_browser_process->IsShuttingDown()) {
LOG(WARNING) << "Not handling interprocess notification as browser"
" is shutting down";
// Send back "SHUTDOWN" message, so that the client process can start up
// without killing this process.
reader->FinishWithACK(kShutdownToken, arraysize(kShutdownToken) - 1);
return;
}
CommandLine parsed_command_line(argv);
PrefService* prefs = g_browser_process->local_state();
DCHECK(prefs);
Profile* profile = ProfileManager::GetDefaultProfile();
if (!profile) {
// We should only be able to get here if the profile already exists and
// has been created.
NOTREACHED();
return;
}
// Ignore the request if the process was passed the --product-version flag.
// Normally we wouldn't get here if that flag had been passed, but it can
// happen if it is passed to an older version of chrome. Since newer versions
// of chrome do this in the background, we want to avoid spawning extra
// windows.
if (parsed_command_line.HasSwitch(switches::kProductVersion)) {
DLOG(WARNING) << "Remote process was passed product version flag, "
<< "but ignored it. Doing nothing.";
} else {
// Run the browser startup sequence again, with the command line of the
// signalling process.
FilePath current_dir_file_path(current_dir);
BrowserInit::ProcessCommandLine(parsed_command_line, current_dir_file_path,
false /* not process startup */, profile,
NULL);
}
// Send back "ACK" message to prevent the client process from starting up.
reader->FinishWithACK(kACKToken, arraysize(kACKToken) - 1);
}
void ProcessSingleton::LinuxWatcher::RemoveSocketReader(SocketReader* reader) {
DCHECK(reader);
readers_.erase(reader);
delete reader;
}
///////////////////////////////////////////////////////////////////////////////
// ProcessSingleton::LinuxWatcher::SocketReader
//
void ProcessSingleton::LinuxWatcher::SocketReader::OnFileCanReadWithoutBlocking(
int fd) {
DCHECK_EQ(fd, fd_);
while (bytes_read_ < sizeof(buf_)) {
ssize_t rv = HANDLE_EINTR(
read(fd, buf_ + bytes_read_, sizeof(buf_) - bytes_read_));
if (rv < 0) {
if (errno != EAGAIN && errno != EWOULDBLOCK) {
PLOG(ERROR) << "read() failed";
CloseSocket(fd);
return;
} else {
// It would block, so we just return and continue to watch for the next
// opportunity to read.
return;
}
} else if (!rv) {
// No more data to read. It's time to process the message.
break;
} else {
bytes_read_ += rv;
}
}
// Validate the message. The shortest message is kStartToken\0x\0x
const size_t kMinMessageLength = arraysize(kStartToken) + 4;
if (bytes_read_ < kMinMessageLength) {
buf_[bytes_read_] = 0;
LOG(ERROR) << "Invalid socket message (wrong length):" << buf_;
return;
}
std::string str(buf_, bytes_read_);
std::vector<std::string> tokens;
base::SplitString(str, kTokenDelimiter, &tokens);
if (tokens.size() < 3 || tokens[0] != kStartToken) {
LOG(ERROR) << "Wrong message format: " << str;
return;
}
// Stop the expiration timer to prevent this SocketReader object from being
// terminated unexpectly.
timer_.Stop();
std::string current_dir = tokens[1];
// Remove the first two tokens. The remaining tokens should be the command
// line argv array.
tokens.erase(tokens.begin());
tokens.erase(tokens.begin());
// Return to the UI thread to handle opening a new browser tab.
ui_message_loop_->PostTask(FROM_HERE, NewRunnableMethod(
parent_,
&ProcessSingleton::LinuxWatcher::HandleMessage,
current_dir,
tokens,
this));
fd_reader_.StopWatchingFileDescriptor();
// LinuxWatcher::HandleMessage() is in charge of destroying this SocketReader
// object by invoking SocketReader::FinishWithACK().
}
void ProcessSingleton::LinuxWatcher::SocketReader::FinishWithACK(
const char *message, size_t length) {
if (message && length) {
// Not necessary to care about the return value.
WriteToSocket(fd_, message, length);
}
if (shutdown(fd_, SHUT_WR) < 0)
PLOG(ERROR) << "shutdown() failed";
parent_->RemoveSocketReader(this);
// We are deleted beyond this point.
}
///////////////////////////////////////////////////////////////////////////////
// ProcessSingleton
//
ProcessSingleton::ProcessSingleton(const FilePath& user_data_dir)
: locked_(false),
foreground_window_(NULL),
ALLOW_THIS_IN_INITIALIZER_LIST(watcher_(new LinuxWatcher(this))) {
socket_path_ = user_data_dir.Append(chrome::kSingletonSocketFilename);
lock_path_ = user_data_dir.Append(chrome::kSingletonLockFilename);
cookie_path_ = user_data_dir.Append(chrome::kSingletonCookieFilename);
}
ProcessSingleton::~ProcessSingleton() {
}
ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcess() {
return NotifyOtherProcessWithTimeout(*CommandLine::ForCurrentProcess(),
kTimeoutInSeconds,
true);
}
ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessWithTimeout(
const CommandLine& cmd_line,
int timeout_seconds,
bool kill_unresponsive) {
DCHECK_GE(timeout_seconds, 0);
ScopedSocket socket;
for (int retries = 0; retries <= timeout_seconds; ++retries) {
// Try to connect to the socket.
if (ConnectSocket(&socket, socket_path_, cookie_path_))
break;
// If we're in a race with another process, they may be in Create() and have
// created the lock but not attached to the socket. So we check if the
// process with the pid from the lockfile is currently running and is a
// chrome browser. If so, we loop and try again for |timeout_seconds|.
std::string hostname;
int pid;
if (!ParseLockPath(lock_path_, &hostname, &pid)) {
// No lockfile exists.
return PROCESS_NONE;
}
if (hostname.empty()) {
// Invalid lockfile.
UnlinkPath(lock_path_);
return PROCESS_NONE;
}
if (hostname != net::GetHostName()) {
// Locked by process on another host.
DisplayProfileInUseError(lock_path_.value(), hostname, pid);
return PROFILE_IN_USE;
}
if (!IsChromeProcess(pid)) {
// Orphaned lockfile (no process with pid, or non-chrome process.)
UnlinkPath(lock_path_);
return PROCESS_NONE;
}
if (IsSameChromeInstance(pid)) {
// Orphaned lockfile (pid is part of same chrome instance we are, even
// though we haven't tried to create a lockfile yet).
UnlinkPath(lock_path_);
return PROCESS_NONE;
}
if (retries == timeout_seconds) {
// Retries failed. Kill the unresponsive chrome process and continue.
if (!kill_unresponsive || !KillProcessByLockPath(lock_path_))
return PROFILE_IN_USE;
return PROCESS_NONE;
}
base::PlatformThread::Sleep(1000 /* ms */);
}
timeval timeout = {timeout_seconds, 0};
setsockopt(socket.fd(), SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout));
// Found another process, prepare our command line
// format is "START\0<current dir>\0<argv[0]>\0...\0<argv[n]>".
std::string to_send(kStartToken);
to_send.push_back(kTokenDelimiter);
FilePath current_dir;
if (!PathService::Get(base::DIR_CURRENT, ¤t_dir))
return PROCESS_NONE;
to_send.append(current_dir.value());
const std::vector<std::string>& argv = cmd_line.argv();
for (std::vector<std::string>::const_iterator it = argv.begin();
it != argv.end(); ++it) {
to_send.push_back(kTokenDelimiter);
to_send.append(*it);
}
// Send the message
if (!WriteToSocket(socket.fd(), to_send.data(), to_send.length())) {
// Try to kill the other process, because it might have been dead.
if (!kill_unresponsive || !KillProcessByLockPath(lock_path_))
return PROFILE_IN_USE;
return PROCESS_NONE;
}
if (shutdown(socket.fd(), SHUT_WR) < 0)
PLOG(ERROR) << "shutdown() failed";
// Read ACK message from the other process. It might be blocked for a certain
// timeout, to make sure the other process has enough time to return ACK.
char buf[kMaxACKMessageLength + 1];
ssize_t len =
ReadFromSocket(socket.fd(), buf, kMaxACKMessageLength, timeout_seconds);
// Failed to read ACK, the other process might have been frozen.
if (len <= 0) {
if (!kill_unresponsive || !KillProcessByLockPath(lock_path_))
return PROFILE_IN_USE;
return PROCESS_NONE;
}
buf[len] = '\0';
if (strncmp(buf, kShutdownToken, arraysize(kShutdownToken) - 1) == 0) {
// The other process is shutting down, it's safe to start a new process.
return PROCESS_NONE;
} else if (strncmp(buf, kACKToken, arraysize(kACKToken) - 1) == 0) {
// Notify the window manager that we've started up; if we do not open a
// window, GTK will not automatically call this for us.
gdk_notify_startup_complete();
// Assume the other process is handling the request.
return PROCESS_NOTIFIED;
}
NOTREACHED() << "The other process returned unknown message: " << buf;
return PROCESS_NOTIFIED;
}
ProcessSingleton::NotifyResult ProcessSingleton::NotifyOtherProcessOrCreate() {
return NotifyOtherProcessWithTimeoutOrCreate(
*CommandLine::ForCurrentProcess(),
kTimeoutInSeconds);
}
ProcessSingleton::NotifyResult
ProcessSingleton::NotifyOtherProcessWithTimeoutOrCreate(
const CommandLine& command_line,
int timeout_seconds) {
NotifyResult result = NotifyOtherProcessWithTimeout(command_line,
timeout_seconds, true);
if (result != PROCESS_NONE)
return result;
if (Create())
return PROCESS_NONE;
// If the Create() failed, try again to notify. (It could be that another
// instance was starting at the same time and managed to grab the lock before
// we did.)
// This time, we don't want to kill anything if we aren't successful, since we
// aren't going to try to take over the lock ourselves.
result = NotifyOtherProcessWithTimeout(command_line, timeout_seconds, false);
if (result != PROCESS_NONE)
return result;
return LOCK_ERROR;
}
bool ProcessSingleton::Create() {
int sock;
sockaddr_un addr;
// The symlink lock is pointed to the hostname and process id, so other
// processes can find it out.
FilePath symlink_content(StringPrintf(
"%s%c%u",
net::GetHostName().c_str(),
kLockDelimiter,
base::GetCurrentProcId()));
// Create symbol link before binding the socket, to ensure only one instance
// can have the socket open.
if (!SymlinkPath(symlink_content, lock_path_)) {
// If we failed to create the lock, most likely another instance won the
// startup race.
return false;
}
// Create the socket file somewhere in /tmp which is usually mounted as a
// normal filesystem. Some network filesystems (notably AFS) are screwy and
// do not support Unix domain sockets.
if (!socket_dir_.CreateUniqueTempDir()) {
LOG(ERROR) << "Failed to create socket directory.";
return false;
}
// Setup the socket symlink and the two cookies.
FilePath socket_target_path =
socket_dir_.path().Append(chrome::kSingletonSocketFilename);
FilePath cookie(GenerateCookie());
FilePath remote_cookie_path =
socket_dir_.path().Append(chrome::kSingletonCookieFilename);
UnlinkPath(socket_path_);
UnlinkPath(cookie_path_);
if (!SymlinkPath(socket_target_path, socket_path_) ||
!SymlinkPath(cookie, cookie_path_) ||
!SymlinkPath(cookie, remote_cookie_path)) {
// We've already locked things, so we can't have lost the startup race,
// but something doesn't like us.
LOG(ERROR) << "Failed to create symlinks.";
if (!socket_dir_.Delete())
LOG(ERROR) << "Encountered a problem when deleting socket directory.";
return false;
}
SetupSocket(socket_target_path.value(), &sock, &addr);
if (bind(sock, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) < 0) {
PLOG(ERROR) << "Failed to bind() " << socket_target_path.value();
CloseSocket(sock);
return false;
}
if (listen(sock, 5) < 0)
NOTREACHED() << "listen failed: " << safe_strerror(errno);
// Normally we would use BrowserThread, but the IO thread hasn't started yet.
// Using g_browser_process, we start the thread so we can listen on the
// socket.
MessageLoop* ml = g_browser_process->io_thread()->message_loop();
DCHECK(ml);
ml->PostTask(FROM_HERE, NewRunnableMethod(
watcher_.get(),
&ProcessSingleton::LinuxWatcher::StartListening,
sock));
return true;
}
void ProcessSingleton::Cleanup() {
UnlinkPath(socket_path_);
UnlinkPath(cookie_path_);
UnlinkPath(lock_path_);
}